Dr. Peterson is an Assistant Professor of Medicine in the Division of Cardiology at Denver Health Medical Center and the University of Colorado Denver (UCD). She has completed a master's in public health and conducted multiple observational studies focused on quality of care and outcomes for patients with heart failure (HF). Dr. Peterson's career goal is to improve the care and outcomes of patients with heart failure by conducting comparative effectiveness research (CER) in HF. Career Development Goals and Training: The proposed K08 career development plan builds on her prior training and experiences in observational research and addresses critical areas for performing robust observational CER. The three principal developmental goals of the application are to acquire: 1) expertise in combining data sources and analytic strategies for accounting for data structure; 2) advanced training in statistical methods for causal inference in observational studies; specifically, methods for addressing confounding, including propensity scores, instrumental variables, and sensitivity analysis; and 3) advanced training in statistical methods for analyzing longitudinal data and methods for handling missing data. Accordingly, Dr. Peterson proposes focused coursework and seminars, contextual learning through the proposed research and mentorship from a team of experts. These training activities will provide experience and skills to perform CER and advance the understanding of the comparative effectiveness of therapies for patients with HF. Mentors/Environment: The primary mentor, Frederick Masoudi, MD, MSPH, is Co-PI of the AHRQ- sponsored multicenter Longitudinal Studies of ICDs (LSICDs) which will provide the data and research infrastructure for this K08. Co-mentor David Magid, MD, MPH is Co-PI of the Cardiovascular Research Network (CVRN) and is Director of Research for the Colorado Permanente Medical Group. Co-mentor Sharon-Lise Normand, PhD is a Professor of Health Care Policy (biostatistics) at Harvard Medical School and Professor in the Department of Biostatistics at the Harvard School of Public Health and an internationally recognized expert in observational CER methods. This mentorship team is highly capable of guaranteeing the completion of Dr. Peterson's proposed research and training activities. A key aspect of Dr. Peterson's research environment is the nationally recognized Colorado Cardiovascular Outcomes Research (CCOR) group. CCOR is a multi-institutional and multidisciplinary group of established cardiovascular outcomes researchers which brings together methodological and content expertise to conduct cutting-edge cardiovascular outcomes research. Another key aspect of the research environment is the Kaiser Permanente Colorado Institute for Health Research (KPCO-IHR) which will serve as the data coordination and analytic center for this proposal. The KPCO-IHR includes 116 investigators supported by research nurses, project managers, research assistants, statisticians, analysis, programmers, IT support and administrative staff. Dr. Peterson has been an Affiliate Investigator since 2005. Dr. Masoudi (primary mentor) is also an Affiliate Investigator and Dr. Magid, a Co-Mentor for this proposal, is a senior investigator at IHR. Research: With the publication of landmark clinical efficacy trials, the use of implantable cardioverter defibrillators (ICDs) for the primary prevention of sudden cardiac death in patients with HF and reduced left ventricular function has increased. However, these trials leave many questions, including optimal device selection, unanswered. More complex dual chamber devices offer theoretical benefits beyond simpler single chamber devices. However, the benefits of dual chamber devices in those without a clear indication (i.e. discretionary dual chamber devices) are not established. The research objectives of this multi-center cohort study are to identify the patient and physician factors associated with the use of discretionary dual chamber device and to compare a) peri-procedural and longitudinal complications, b) hospitalizations, c) mortality, and d) inappropriate shocks among those receiving single chamber ICDs and similar patients receiving discretionary dual chamber devices in a large, broadly representative community-based HF population. Summary: This mentored research and training proposal is also directly responsive to AHRQ's mission to improve the quality, safety efficiency and effectiveness of health care, and is specifically responsive to the comparative effectiveness priority area by proposing to 1) understand the patterns of appropriate and discretionary use of dual chamber ICDs in community-based populations and identify the demographic and clinical factors associated with the discretionary use of a dual chamber device; 2) determine the comparative safety of single and dual chamber ICDs; 3) generate critical insights on the clinical comparative effectiveness of single and dual chamber ICDs; and 4) evaluate outcomes important to stakeholders. Further, this award will facilitate Dr. Peterson's development into a nationally-recognized independent comparative effectiveness investigator in cardiovascular disease.